The present invention relates to a new and improved construction of a filter box for textile machines, which filter box is of the type comprising an inlet connection, a filter element equipped with means for cleaning the filter element, an outlet opening at the clean air side and an outlet opening at the raw air side of the filter element, as well as a ventilator or fan.
There are already known to the art filter boxes of the previously mentioned type, wherein, for the purpose of cleaning the filter element, there is produced a cleaning air current, for instance by switching flap valves. This cleaning air current flows in a direction opposite to the work air current. The fibers which arrive at the raw air side and the contaminants are periodically removed. Removal of such contaminants either is accomplished manually or pneumatically, in the event that the filter box is connected at a central suction installation having a fiber depository.
The state-of-the-art filter boxes can be used successfully in those instances where the pressure surges or pressure fluctuations at the suction locations of the connected machine or machines do not have any disturbing effect upon the work process which occurs at such machine or machines. These pressure fluctuations, apart from the gradual covering or coating of the filter element, are particularly caused by the periodic cleaning of the filter element, i.e., the removal of the fibers and contaminants by emptying the raw air compartment.
When using such type filter boxes in conjunction with certain spinning preparatory machines, e.g. drafting arrangements, it has been found however that such pressure fluctuations can lead to interruptions in the work process, for instance due to slubbing or sliver rupture.
What is also disadvantageous is that the automatic cleaning and emptying of such filter boxes requires the connection at the suction installations by means of complicated tubular conduits or the like. Furthermore, the suction installations, in turn, must be equipped with dust filters and devices for cleaning the same, in order to reclaim the separated fibers.